Diisopropylaniline → 2,6-Diisopropyl-N-((2-isopropylphenyl)(6-(2-((phenylamino)methyl)naphthalen-1-yl)pyridin-2-yl)methyl)aniline

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Reaction Conditions

Reaction Steps

Compound 5a (2.28 g, 5.18 mmol), tetrahydrofuran (50 mL), and 4 angstrom molecular sieves (ca. 20 mL) were combined. Then 2,6-diisopropylaniline (0.918 g, 5.18 mmol) and a catalytic amount of p-toluenesulfonic acid monohydrate (0.005 g, 0.03 mmol) were added. The mixture was heated to 45° C. for 14 hours. Then the mixture was filtered and fresh molecular sieves (ca. 15 mL) were added followed by additional p-toluenesulfonic acid monohydrate (0.005 g, 0.03 mmol). After heating at 50° C. for 2 hours the mixture was filtered and evaporated to a residue of the imine 6a. Then Et2O (30 mL) was added, and the resulting solution was cooled to −80° C. An Et2O (5 mL) solution of 2-isopropylphenyllithium (0.653 g, 5.18 mmol) was added dropwise. The mixture was then allowed to slowly warm to ambient temperature over a couple of hours. Then the mixture was poured into water (100 mL) and the organics were separated, dried over brine then magnesium sulfate, filtered, and evaporated to a residue. The residue was dissolved in chloroform (25 mL), and trifluoroacetic acid (10 mL) was added. The mixture was heated to reflux for 40 minutes, during which time gas evolved. The mixture was cooled to ambient temperature and 3 M NaOH (60 mL) was added. After stirring for several minutes, the organics were separated, dried over brine then magnesium sulfate, filtered through diatomaceous earth, and evaporated to yield the crude product. This was purified by chromatography on basic alumina using 5:1 hexanes:CH2Cl2 with an increasing gradient of ethyl acetate (1% to 10%). The product was isolated as a foam-like solid. For 1H NMR (in CD2Cl2) see FIG. 4.

Provenance & Evidence